1. Field of the Invention
This invention relates to a data controller for controlling transfer of data between a host computer and input/output units in a print system consisting of a host computer, a printer, a scanner, and the like and further relates to a printer and a print system that can also be used as a copier making it possible to copy an image read through a scanner, namely, make a local copy as well as print the print data from a host computer by providing such a data controller.
The present application is based on Japanese Patent Applications No. Hei. 11-196773 and 11-196774, which are incorporated herein by reference.
2. Description of the Related Art
Hitherto, in a print system comprising a printer and a scanner connected to a host computer via a network or locally, the printer has received print data prepared using application software, etc., on the host computer or print data provided by editing image data read through the scanner on the host computer, has interpreted the received print data, and has driven a print engine, thereby executing predetermined print on a print record medium.
From the host computer, data other than the print data can also be transmitted to the printer. For example, the host computer can also make an inquiry about various statuses of the printer (paper remaining amount, ink remaining amount, etc.,). The host computer can also request the printer to urgently stop print, etc.
On the other hand, in recent years, particularly the image quality of a color ink jet printer has been improved remarkably, thus if the color ink jet printer is used in combination with a scanner, a large number of users can also easily get a high-quality color copy without purchasing an expensive color copy machine.
However, to thus use the printer and the scanner, a large installation space becomes necessary and in addition, programs (drivers) for controlling the printer and the scanner must be installed in the host computer. If the same copy as an original image is simply required without editing, etc., the original image, the image data read through the scanner needs to be converted into data that can be interpreted by the printer through the host computer, thus the throughput until a color copy is obtained must be prolonged.
On the other hand, recently, to improve the responsivity of two-way communications between a host computer and a printer, a proposition to adopt IEEE (Institute of Electrical and Electronics Engineers) 1284.4 protocol, etc., for data communications therebetween and execute packet communications has also been made. Such a proposition makes it possible to assign more than one logical channel to a physical interface between the host computer and the printer, transmit print data to the printer, for example, and transmit an urgent print stop command, various status requests, etc., to the printer even before completion of transmitting the print data.
Recently, a LAN (local area network) has been constructed for often sharing one printer and one scanner, for example, by a large number of host computers. In such a case, further, to also use the printer in combination with the scanner as a copy system as described above, when one user stands in front of the scanner and reads an image through the scanner and prints a copy of the read image on the printer, another user may operate the host computer to issue a status request to the printer. Hitherto, however, an effective proposition to efficiently control transfer of data in such a case and also respond more promptly to the status request as described above has hot been made.